Patent GB-829765-A (GB)
Title: A control system for a machine tool
IPC: G05B19/04
Filed: 1957-05-23
Abstract: 829,765. Copy-milling. KEARNEY & TRECKER CORPORATION. May 23, 1957 [Sept. 4, 1956], No. 16377/57. Class 83 (3). A milling or other machine tool having a plurality of members carried for rectilinear movement along different paths, comprises separate transmission mechanisms (fluid-operated clutches) connectable to move a respectively associated one of said members in either direction along their paths of travel, a sequence controller 553, Fig. 12C, indexably advanceable in a step-by-step movement to a plurality of stations, said controller being operative at each station to actuate a preselected one of said transmission mechanisms for moving the associated member in a selected direction, presettable selector means 554 operative to selectively vary the sequence in which said transmission mechanisms are actuated by said controller and control means (dogs and switches) associated with each of said members and operable in response to a preselected position of its associated member to effect a single step advancement of said sequence controller to thereby interrupt the movement of said associaated member and initiate the succeeding movement of a member as established by said selector means. An axially-movable tool spindle 25 and a tool drive motor 26 are carried on a head 23 movable vertically by an hydraulic motor 230 under the control of a tracer 35 and pattern 36. A work-table 29 is traversed by a motor 30 through variable-speed means 31. The machine may operate by push-button control or in a single, or continuous, cycle. The table 29 and head 23 each carry adjustable dogs.687, 843, Figs. 3 and 4, to co-operate with an aligned series of switches 32, 37 to operate solenoid-valves to change the speed of, to stop, or to initiate a movement or to render the copying means effective. The change-speed means for the table 29 comprises a gear 47, Fig. 5, driven by the motor 30, a shaft 50 driving a gear 51, a change-gear feed-box 55 having an input gear 52 meshing with the gear 51 and an output gear 59 driving, through a gear 60, a gear 64 having a gear 66 fast therewith. The gear 66 provides the feed drive and a gear 67 fast on the shaft 50 provides the rapid traverse drive. The gears 66, 67 rotate twin gears 81, 82 engaging a pair of nuts 72, 73 engaging a fixed screw 69, back-lash being eliminated by a device 75. The feed or rapid traverse drive is selected by a clutch 93 moved to right or left by fluid pressure supplied through lines 97, 98. The direction of rotation of the nuts 72, 73 is selected by clutches 112, 113 engaged against spring pressure by fluid pressure supplied through lines 134, 135. Both clutches 112, 113 are normally engaged to lock the table 29 in an adjusted position. The fluid-pressure is supplied by a pump driven by the motor 30. For controlling rotation and movement of the spindle, fluid-pressure is supplied by a pump 150, Fig. 6, rotated by the motor 26. Energization of the motor causes automatic engagement of either a spindle-drive clutch 154 or a spindle-brake clutch 158. With the clutch 154 engaged, the spindle is rotated in a quill 34 through changegears 156, 178, and shifting gears 182, 183. In its forward cutting position, the quill 34 is clamped by a split sleeve 190 tightened by a screwed rod 191 engaged by a nut rotated by a lever moved by a fluid-operated piston. When the piston is operated to release the clamp, a piston 198 is subsequently moved to relieve the cutter by withdrawing the quill through rack- and-pinion gearing 193-197. The rack 197 carries a projection 975 co-operating with switches 973, 976 to signal movements of the quill. The hydraulic motor 230, Fig. 7, is supplied with fluid by a pump and motor unit 454, 455, Fig. 1, and is connected to a screw 239, for vertically moving the head 23, by an hydraulically-operated clutch 236. The head is counterbalanced by fluid supplied at high pressure to the top of a stationary piston 266 wherever the motor 230 is actuated or when a hand crank is inserted in the end of a shaft 250 for adjusting the head manually. The high pressure is obtained by operating a relief valve which is normally effective to cause a lower pressure to be applied to the piston. A solenoid-operated valve 467, Fig. 11, connected in a circuit between the pump 455 and the motor 230 determines whether vertical movement of the head is to be under the control of the tracer 35 or of a directional valve 470. When the valve 467 is operated to supply fluid to the valve 470, the head 23 is moved at a fast rate via a solenoid-operated valve 478, or if the valve 478 is reversed, at a feed speed controlled by a valve 480. When copying is to take place, the valve 467 together with valves 498 and 499 are reversed. These valves may be operated automatically by the dogs and switches so that the head approaches the work at a fast rate until the tracer approaches the pattern 36. In push-button operation, the table or head can be moved in either direction at feed speed by four buttons, the movement continuing until a switch is operated by a feedlimiting or an over-travel dog or until a traverse stop button is pressed. Depression of a rapid traverse switch causes any feed movement to continue at rapid rate until the button is released. A main selector switch, when closed, renders the push-buttons ineffective and conditions the machine for automatic operation. For operating with a programmed cycle, there are provided a selectively energizable stepping switch 553, Fig. 12C, having three wiper arms 858, 859, 860, a number of function selector switches 554 and three control relavs 555 for energizing the switch 553. With the function selector switches and the machine dogs appropriately set, a traverse start button is pressed to operate a relay 856 and connect the selector switches with the appropriate solenoids. In single cycle operation, the traverse start button has to be pressed consecutively to step round the switch 553 by means of a pawl rod 911 moved downwardly by a solenoid 914 and upwardly, on the operative stroke, by a spring 915. In continuous operation, a switch 920 is closed. Each function selector switch has two arms 887, 887a and is set to one of the positions shown in Fig. 17 by a knob 884. Any switch can be cut out by setting the knob 884 to " Reset." Indicator lights 956-966 energized through the arm 860 show the progress of the machine cycle. Push-buttons are provided to stop, and to continue, a cycle at any stage. However, if after a cycle has been interrupted, the main selector switch is operated to enable pushbutton adjustments to be made, the cycle cannot be accidentally continued, as operation of the main selector switch returns the stepping switches to their initial positions. A cycle is completed when a cam 929 fast with the switcharm 858 releases a switch-rod 922. A " split " cycle may be performed in which a knob 884 is set at " Stop." The work-table, which may carry two workpieces, is then repositioned before the second part of the cycle is resumed. Specification 829,766 is referred to.